Crisscross method
Encyclopedia
The Crisscross method is a method of finding out the chemical formula
of a metal and non-metal that combine to form an ionic bond.
To use this method, the absolute value of the oxidation number
of the first ion is used as the subscript of the second, and vice versa. The subscripts are then reduced by the greatest common factor. For instance, to find the formula for magnesium oxide
The first word is the metal, which retains its name.
The second word is the non-metal, which retains its element prefix and add ...IDE as its suffix.
The subscript number of an element doesn't affect the name
e.g.: a. Al3 S2-
Al2 S3
Which then becomes Aluminum Sulfide
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
of a metal and non-metal that combine to form an ionic bond.
To use this method, the absolute value of the oxidation number
Oxidation number
In coordination chemistry, the oxidation number of a central atom in a coordination compound is the charge that it would have if all the ligands were removed along with the electron pairs that were shared with the central atom. Oxidation numbers are often confused with oxidation states.The...
of the first ion is used as the subscript of the second, and vice versa. The subscripts are then reduced by the greatest common factor. For instance, to find the formula for magnesium oxide
Magnesium oxide
Magnesium oxide , or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium . It has an empirical formula of and consists of a lattice of Mg2+ ions and O2– ions held together by ionic bonds...
The first word is the metal, which retains its name.
The second word is the non-metal, which retains its element prefix and add ...IDE as its suffix.
The subscript number of an element doesn't affect the name
e.g.: a. Al3 S2-
Al2 S3
Which then becomes Aluminum Sulfide
External links
- Formula Writing, SparkNotes